A new cyber threat actor, TAG-150, has emerged since March 2025, utilizing a sophisticated multi-tiered infrastructure and custom malware, including CastleLoader, CastleBot, and CastleRAT. TAG-150's infrastructure consists of four tiers, including command-and-control servers and intermediary layers to obscure operations. The CastleRAT trojan, available in Python and C variants, features advanced capabilities such as stealth evasion, system information collection, and remote surveillance functions. TAG-150 employs phishing techniques and fraudulent domains to compromise victims, achieving a 28.7% infection rate among those who interact with their schemes. The group utilizes privacy-focused services and frequently relocates its infrastructure to evade detection. Experts recommend proactive measures to counteract TAG-150's activities, including blocking identified infrastructure and monitoring for data exfiltration. Indicators of compromise include specific IP addresses associated with CastleLoader.